Pages

Sunday, 31 August 2008

The fungal season is well underway, and I found a new species for my list on my first little foray of the year. This is the Earth Fan - Thelophora terrestris. It apparently grows in soil, as seen below, but it tends to form tiers in a straightish line, so I think it's on submerged dead wood. The moss is young Pleurozium schreberi.

The Deceiver - Laccaria laccata - is a very common fungus that can be found anywhere from the youngest plantation to the oldest forest. This is its close relative Laccaria proxima. The most obvious difference is the much darker (and more fibrous) stipe, which can just be seen in the shot below. It inhabits mossy and peaty heath, which is exactly where I found it.

The Hoverfly Rhingia campestris has a distinctively large, pointed, snout. I always wondered why until I saw them nectaring in close-up: they have this enormous nectaring tube that folds away for storage. The flower is Devilsbit Scabious.

I also spotted this recently-emerged Angle Shades moth. Newly emerged specimens have the pink and olive markings, slightly older specimens have only shades of orange/rust.

There's a lot going for the next photograph. The Dungfly Scathophaga stercoraria has caught another fly and is consuming it, hidden deep inside the flowerhead of Angelica. I had to use manual focus to get the shot, squeezed through a gap between the framing flowerheads at the front.

I love the newly-formed seeds of the Angelica that act as a platform for the Dungfly.

Thursday, 28 August 2008

There are a few people who are always on the lookout for new species for me. A 'phone call alerted me to the presence of a "quair nettle with purple and yellow flowers" growing in a nearby lawn. So I shot off and found a new species for my list: Large-flowered Hemp Nettle - Galeopsis speciosa.

Friday, 22 August 2008

The fungal season is almost upon us, and I'll have to swap in that part of my brain again. Fungi are, of course, with us all year round, but autumn is the time of year when most of the larger fungi begin to appear. Panaeolus sphinctrinus grows on dung...this was on a pile of horse-dung that I've been monitoring for perhaps two weeks. I'd expect to find some Coprinus sp. on it soon.

The chequered surface of this leaf mine leads us immediately to Phyllonorycter ( a family of tiny micromoths), and this is on Beech, with a single fold in the lower surface, so we are left with Phyllonorycter messaniella.

The fold decreases the area of the lower leaf, curling it and leaving the upper side with a bubble for the moth to move around in. The fold can clearly be seen in the lower picture.

This is the wonderful hoverfly Sphaerophoria scripta (female). These are very flighty, and good shots are rare.

Thursday, 21 August 2008

The last couple of posts were about Ichneumonids, which are parasites on the larvae of other insects. This Tachinid Fly is another:

Tachinids are fairly easy to identify: they have very long spines all over their body. Their flying habit is also easily recognisable, once identified: they fly low and slow over vegetation, looking for their hosts, and dart under leaves very suddenly, just like Ichneumonids. Tachinids are ectoparasites: they lay their (multiple) eggs on the outside of the host larvae. The Tachinid larvae then hatch out and eat the host while it is still alive. This can result in a very messy corpse indeed.

Moving on from parasites, we come to predators. Everyone knows about mimicry, where a harmless insect, such as a hoverfly, can have black and yellow bands just like a wasp. This similarity affords the hoverfly protection from predators such as birds, which avoid eating insects that might be unpleasant or harmful. In the following case, however, we have the reverse situation. This is an Ectemnius sp. wasp:

A few points are worth noting:

1) the body is black and yellow, as you might expect from a wasp, but the yellow bands are very rounded.

2) the head is very large, giving the impression of large eyes.

3) the antennae are bi-coloured, hinge in the middle, and can be pulled up into notches in the 'face', leaving a yellow area in the middle of the face.

Has this rung any bells yet?

Going back to the points above:

1) the yellow bands on hoverflies can be rounded.

2) hoverflies have large eyes

3) hoverflies have short antennae that sprout from the top of the head, and often have a yellow face.

So the inescapable conclusion is that this is a wasp which is trying very hard to look like a hoverfly.

Why?.....because it is predatory only on hoverflies, which it catches and then feeds to its young. It resembles a hoverfly so that it can sneak up on them and catch them unawares.

So here we have a wasp that is pretending to look like a hoverfly that is pretending to look like a wasp. Talk about a wolf in sheep's clothing...

Tuesday, 19 August 2008

Ichneumonids are parasitic wasps which lay their eggs directly into the larvae of butterflies, moths, flies and sawflies, although some are hyperparasites (laying their eggs into the larvae of primary parasites), and a few are paraparasites ( laying their eggs into the larvae of hyperparasites). The host is always eventually killed by the parasite, usually in the pupal phase. Most Ichneumonids lay a single egg in each host, although some lay multiple eggs, and there are over 1750 different species in UK and Ireland, ranging from 2-3mm up to the largest at 8cm long. Due to the fact that the various different families converge on a very small number of colour patterns, identification is very complex and always requires trapping, killing and microscopic investigation. There are very few people who have embarked upon the years of study required to investigate this group, so they are relatively poorly understood. If I had a spare life I would certainly give them a go, because I find them absolutely fascinating. Their form varies enormously, although they all have long antennae and a very narrow 'waist' between the thorax and the abdomen. The nature of the host can usually be determined by looking at various characteristics of the parasite: size, length of legs, length of ovipositor.

I photographed this beauty last night:

Based on the size (3 cm. from nose to tail) alone, this one requires a very large host, and it will almost certainly parasitise one of the larger moths, such as the Drinker or Northern Eggar. The larva of the Elephant Hawk Moth is parasitised by the similarly-sized black and white Ichneumon Amblyjoppa proteus. [http://homepage.eircom.net/~hedgerow14/may30.htm shows the emergence sequence]

The next is a Macrocentrus sp., and the structure of the body is very carefully arranged: she has massively long antennae, very long rear legs and a very long ovipositor. These lay their eggs into fly and moth larvae hidden deep inside the seedheads of Thistles and Knapweed. The long legs are required to give her body enough clearance to spin the ovipositor 180 degrees towards her antennae.

Monday, 18 August 2008

In February, I posted about hyperparasitic Ichneumonids, and yesterday the story took a further amazing twist.

To summarise, the Ichneumonid I had been following was a hyperparasite, which was targetting the larvae of the primary parasite already inside the sawfly larva. Since then I have been searching for the primary parasite to complete the picture.

Yesterday I found a new Ichneumonid ovipositing in the sawfly larvae, but the ovipositing process was the most bizarre I've ever seen. This is a shot taken from below the leaf:

The Ichneumonid is under the leaf, with her abdomen curled round the edge of the leaf and ovipositing into the larva, which is above the leaf. I've seen these long-abdomened wasps before, but didn't know why the abdomen was so long. Now I know.

Just in case there's any doubt, here's the ovipositor in action:

This shot shows the Ichneumonid leaving the scene after her work was done:

Thursday, 14 August 2008

It's still early days in my moth career. Some are fairly easy to identify, but others can be much more troublesome due to:

variations within species (size, colour, pattern)

similarities between species

wear

changes in phenology due to warming

Much of the identification process relies on experience and repeated exposure to conflicting identifications: yesterday I read a post on UKmoths where five experts gave five different suggestions for one worn specimen.

The Northern Eggar/Oak Eggar complex is rather interesting: the life-cycle is either 1 year (mostly southern) or 2 year (Northern/Western), but the intermediate zone (English midlands/Welsh border) has populations that vary between 1 year and two years. I rather suspect we're seeing the intermediate stage of one species becoming two. There are, however, consistent variations in size and pattern between the two subspecies. I've chosen Northern Eggar for this one simply because that's what we have in Ireland, but the rear of the main yellow band is diffuse, which ties in perfectly. It should be noted that these are day-flying moths and can often be confused in flight with larger butterflies, especially Dark Green Fritillary.

Tuesday, 5 August 2008

My main set up is a Canon EOS 350D with a Canon 60mm USM Macro lens. The effective focal length of the lens is 90mm., due to the 1.5 x multiplier on small-sensor Canon SLRs. This lens gives me the possibility to capture objects 1:1 on the sensor. USM stands for Ultrasonic Motor, which I'll come back to later. This set up isn't exactly compact, but it is handy and delivers the results you've seen since January 2007. Here's a look at it:

Prior to 2007, I used the Fuji s7000 as my main camera, and I loved it dearly. It's certainly easier to use (and it's cheaper), but the images, whilst very good, don't have the wow factor of the DSLR images.

Methodology

All of my shots are hand-held, so I need to set exposure to at least 160th to eliminate handshake. That means I work almost entirely at Shutter priority, leaving the camera to work out aperture. The depth of field (DOF) on a macro lens is very small indeed, so I need as much light as I can when shooting at a relatively high speed, because the aperture will automatically be opened up to compensate for the fast exposure and, sadly, DOF only increases with smaller apertures. I've experimented with different ISO and always shoot at ISO 400: ISO 1600 gets a bit too grainy for me. Depth of field is still, however, very small even at ISO 400. In order to reduce the effect of reduced DOF, I don't go in as close as I can, preferring to stay further away and crop later. The resolution of the sensor (8 megapixel) means I can crop without losing much definition.

I shoot with autofocus when I can, and the USM motor is extremely fast and very accurate. If I have to shoot on manual focus, that is quick and easy, too, with the switch being under my left thumb, on the barrel of the lens. Another good feature of the lens is that it has manual override on autofocus. In other words, I can use autofocus to get in quick and then fine-tune the focus manually without the camera complaining and trying to refocus automatically.

I tend to shoot more frames than I need, but with Digital who cares?

For flash, I just use the built-in flash unit, and it seems to work satisfactorily. I like to soften flash when I can and I usually work with a single layer of tissue paper stuck onto the flash (I just lick it first).

Although the low DOF more or less demands that I get perpendicular to my subject, I try to make sure that the surface I'm shooting (e.g. a moth wing) is also not flat on to the lens. That helps to make sure that the glare doesn't get reflected back to the camera.

For the computer work I use Photoshop CS2, but I keep my post-processing to an absolute minimum, usually just a crop and resize, with perhaps a tiny bit of brightness/contrast fine-tuning. I really believe that getting the shot correct in the camera is the right way to go. I work entirely in .jpg. I have tried RAW, but didn't find the (very slight) increase in quality was worth all the post-processing effort.

In terms of finding material to shoot and making identifications, that would take a book to cover.

Saturday, 2 August 2008

I took this shot of the Sexton beetle Nicorophorus vespilloides when it flew into me as I was photographing moths at light:

Eagle-eyed readers will have already spotted the Phoretic mites on the elytra (and one at the back of the head):The mites are not parasitic on the beetle, but are carnivorous, eating fly larvae that could be a threat to the beetle larvae. They use the beetle as transport, so we have a good symbiotic relationship, here.

I also coincidentally photographed this Harvestman with phoretic mites on the same day:

Friday, 1 August 2008

I've had this micro before: Dipleurina lacustrata. I've only ever seen it attracted to light (and in fact had one fluttering over the surface of my monitor last night).

The micromoth Apotomis semifasciana is a Willow feeder:

Golden-rod Pug - Eupithecia virgaureata, which is known to feed on Ragwort and Goldenrod. In my location it has to be Ragwort:

I have to say I find Pugs very difficult. The best advice I can give is to read the text descriptions of the key differentiators: examination of markings and comparing then with pictures alone isn't going to get you very far. One of the key identifiers on this specimen was the tiny tuft of pale scales at the rear of the thorax!

The Spectacle - Abrostola tripartita - was very active, flying around the light (and frequently bashing into the glass with a loud thump).